School of Chemistry & Physics

Professor Francesco Petruccione (left) introduces Emeritus Professor John Hey.

Chronology in Greco-Roman Antiquity Featured in Captivating Lecture

Senior Research Associate in the School of Chemistry and Physics (SCP), Emeritus Professor John Hey, delivered a fascinating account of Chronology in Greco-Roman antiquity during his Royal Society of South Africa (RSSA) public lecture on the Westville campus.

More than 50 people, including school-teachers, attended the lecture during which Hey used the revelations illuminated by a sundial unearthed at Pompeii in 1865 as an illustration of how concepts of time are constructed. The main part of the lecture was devoted to the era when the Greek language was the primary means of communication in culture, science and philosophy in much of Europe, Asia Minor, the Middle East and North Africa, especially Egypt.

‘It’s very seldom that we have interdisciplinary interaction and the aim is to make contact between the sciences and the arts, and between the sciences themselves,’ said Hey, whose presentation covered aspects of history, language and the classics.

Hey, a long-standing member of the RSSA, set the scene for the development of time-keeping and how it influenced life; describing the foundations of modern time-keeping based upon electromagnetism and theories of General and Special Relativity.

He gave a brief history of the development of mechanics that took civilisation away from measuring time by the heavenly bodies and toward ancient devices like the hourglass (or sand-thief) and water clocks such as Al-Jazari’s Elephant Clock. Pre-dating these devices was the sundial and Hey gave an account of its development from ancient Egyptian and ancient Greek designs, like that at Pompeii, to sophisticated Moorish designs.

‘The sundial was an expression of the triumph of Greek mathematics which was a mathematics of geometry that achieved enormous success,’ said Hey.

He explained the two aspects of time; chronological time (chronos), more similar to how we understand time of a fixed duration; and auspicious time (kairos). Kairos was described in terms of the seasonal passage of the sun, moon and planets through the zodiac which was used to guide the choice of auspicious hours for decisions and undertakings.

Hey spoke about the eruption of Vesuvius in AD 79 and the subsequent devastation of the city of Pompeii, describing detailed calculations for the epoch just prior to the volcanic eruption of the astronomical coordinates of representative stars in the constellations recorded on the sundial as well as the solar co-ordinates required for the evaluation of the shadow markings.

‘This ancient information has diffused into many branches of science so is something that unites us and the information passes on independently of culture, reflecting the harmony of science that rises above political differences,’ said Hey.

‘This presentation is useful in the context of global knowledge about science and how it has influenced our livelihoods, particularly concerning innovations,’ said Deputy Vice-Chancellor of the College of Agriculture, Engineering and Science Professor Albert Modi.

Words: Christine Cuénod

Photograph: Albert Hirasen